<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<input type="text">
<input type="button" value="按钮" onclick="fn()">
<div></div>
<script src="../jq.js"></script>
<script>
    function fn() {
        /*let info =  $("input:first").val();
        alert(info);*/

        /*修改文本框的值*/
        /*$("input:first").val("啦啦啦");
         */
        /*取出文本框的值给到div*/
        $("div").text($("input:first").val());
    }
</script>
</body>
</html>